The effect of increasing intakes of plant protein on the protein quality of Canadian diets

The 2015 Canadian Community Health Survey was used to investigated the protein content and protein quality of the diets consumed by adults (≥ 19 years) when plant protein is increased. Individuals (n=6498) were allocated to quartiles of increasing proportions of protein from plant foods (Q1:0-24.9%; Q2:25%-49.9%; Q3:50-74.9%; Q4:75-100%). The Protein Digestibility Corrected Amino Acid Score (PDCAAS) of diets were estimated using indispensable amino acid concentrations of foods and an assumed digestibility coefficient of 0.8. Corrected protein intakes were determined by aggregating foods consumed over 24hrs and as the sum of corrected protein consumed at eating events within six, four-hour time intervals. Most individuals (51%) consumed 25-49.9% of protein from plant foods. Cereal-based foods represented the majority of plant protein consumed. PDCAAS of diets remained ≥0.87 for Q1-3, but decreased (p<0.0001) to 0.71±0.018 in Q4 vs. Q2 (0.96±0.004). Corrected protein intakes in Q2 (80.66±1.21 g/day; 1.07±0.03 g protein/kg BW) decreased to 37.13±1.88 g/day (0.54±0.03 g/kg BW) in Q4 (p<0.0001). Aggregated daily corrected protein intake strongly correlated (r=0.99; p<0.001) with the sum of corrected protein consumed within time intervals. Intra-time interval analysis revealed that the relative proportions of animal and plant proteins changed at eating events over 24hrs; and did not reflect the allocation to quartiles based on the daily proportion of plant protein consumption. Various tools should be explored and developed to assist Canadians in effectively incorporating plant protein foods into dietary patterns. Novelty: ●Corrected protein intakes decreased as plant protein consumption increased. ●PDCAAS was ≥0.87 for diets with ≤74.9% plant protein.